1. Field of the Invention
This invention relates, in general, to hydraulic couplings, and specifically to hydraulic couplings used in undersea drilling and production applications. More particularly, the invention involves a remote bleed valve for a subsea hydraulic coupling for bleeding off hydraulic pressure and preventing sea water from entering the hydraulic system when the members of the coupling are disconnected.
2. Description of the Related Art
Subsea hydraulic couplings are old in the art. The couplings generally consist of a male member and female member with sealed fluid passageways connecting therebetween. The female member generally is a cylindrical body with a relatively large diameter longitudinal bore, or receiving chamber, at one end and a relatively small diameter longitudinal bore at the other. The small bore facilitates connections to hydraulic lines, while the large bore seals and slidingly engages the male member of the coupling. The male member includes a cylindrical portion at one end having an outer diameter approximately equal to the diameter of the large bore in the female member of the coupling. The male member also includes a connection at its other end to facilitate connection to hydraulic lines. When the cylindrical portion of the male member is inserted into the large bore of the female member, according to various embodiments of the device, fluid flow is established between the male and female members.
The male and female members of a hydraulic coupling each typically include a poppet valve slidably received within the bore of each member. Each poppet valve typically includes a conical valve face which seats, in the closed position, against a valve seat in the bore. The poppet valve opens to allow fluid flow, and closes the poppet valve face against the corresponding valve seat within the bore to arrest the flow. Generally the poppet valve is spring biased to the closed position. The valve also includes a valve actuator which may be a nose or stem extending from the apex of the valve face along the longitudinal axis of the poppet valve. Contact between the valve actuators of the male and female member poppet valves forces each valve face away from the valve seat and into the open position for fluid flow between the members.
Typically, the male members and female members are attached to opposing manifold plates. In emergency situations, for example storms, fires, hurricanes, etc., the manifold plates are quickly separated and the male and female members are disconnected. When the male and female members are disconnected, particularly in emergency situations, problems arise as a result of trapped hydraulic pressure in the lines. If hydraulic pressure is trapped subsea, the settings of various valves throughout the hydraulic system have a tendency to change in response to the built-up pressure. It is undesirable for the valve settings to unpredictably react to this trapped pressure, so to relieve the pressure it has been suggested to bleed the hydraulic lines that are trapped subsea. Bleeding the lines also is done to avoid damage from blowouts to the hydraulic system. Therefore, if the hydraulic system is in danger of being severed or otherwise damaged due to storms, it then is desirable to disconnect the members and check off or seal one member while allowing the other member, which remains subsea, to bleed off trapped hydraulic pressure. At the same time, it is undesirable for sea water to enter the system through the coupling member that remains subsea.
Bleeding off of trapped hydraulic pressure solves the problem of dangerous high pressure in the hydraulic system which often may result in blowouts to the hydraulic system as well as unpredictable shifting of valve settings. Preferably, to prevent seawater from entering the hydraulic system during bleeding, the bleed passage should include a check valve which permits flow in one direction only. The present invention solves all of these needs and requirements.